1. Field of the Invention
The present invention relates to a vacuum pressure forming device of a vehicle and, more particularly, to a vacuum pressure forming device of a vehicle capable of forming a brake vacuum pressure by using an electric supercharger when necessary.
2. Description of Related Art
In a vehicle, generally, ambient air is introduced into the vehicle, mixed with fuel, and supplied to an engine, and the engine burns the mixture of air and fuel to obtain power required for driving the vehicle.
For combustion in the course of generating power by driving an engine, ambient air must be sufficiently supplied to obtain a desired output and combustion efficiency of the engine. Thus, in order to increase combustion efficiency and enhance an output of an engine, a supercharger or a turbo charger that pressurizes air for combustion and supplies the pressurized air is applied to a vehicle.
The supercharger has a structure compressing air to be supplied to an engine by using pressure of an exhaust gas discharged from the engine.
However, there is a limitation in compressing intake air with only pressure of exhaust gas and supplying the same to an engine according to a running situation of a vehicle, so recently, an electric supercharger that drives a compressor by using an electric motor to compress intake air and supplies the same is applied to a vehicle.
In a vehicle employing the foregoing turbo charger or supercharger, when a driver manipulates a brake pedal in a state in which he or she steps on an accelerator pedal to its maximum level to make an engine enter a wide open throttle (WTO) region, static pressure formed in an intake manifold is not smoothly discharged, failing to form sufficient vacuum pressure for boosting a brake, so the brake is pushed out.
Also, for example, even when a vehicle is run on a high ground, vacuum pressure formed by an intake manifold may not be sufficient for boosting a brake.
The failure of smoothly performing a brake boosting operation due to insufficient vacuum pressure therefore formed by the intake manifold and supplied to a brake device may be vital for a safe operation of a vehicle, and thus, a vacuum pump for sufficiently supplying brake vacuum pressure is installed in a vehicle.
However, an installation of a vacuum pump to form vacuum pressure for brake boosting operation may increase a weight and cost of a vehicle, for which, thus, an improvement method therefore is required.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.